1. Field of the Invention
The present invention relates to a method for detecting a document size and, more particularly to a method for detecting a document size when the width of a document to be scanned is smaller than an effective scan width of a scanner module.
2. Description of the Related Art
Nowadays, office automation facilities such as a printer, scanner and a facsimile have been widely used. In order to extend their own functions, each of the office automation facilities is developed to have high performance and thereby costly products are manufactured. On the other hand, to reduce user's economic burden, the office automation facilities which are separately used are developed integrally. Such a device is conventionally indicated as a multifunctional machine.
A known multifunctional machine integrates a print head using an ink jet printing method and a scanner module of shuttle type. The print head and the scanner module are established in one set, and print on a recordable medium or scan a document by performing reciprocating motion in a same path. At this time, the traveling direction of the print head and scanner module is transverse to the direction to which the recordable medium or the document is transported. The print head and the scanner module are moved simultaneously by one motor.
As is well known, a background of the document scanned by the scanner module is supported by a supporting plate. Conventionally, since a white roller is used as the supporting plate in the multifunctional machine having an array type scanner module, in the case of parts other than the scanned range, it is recognized as having no data by data-processing suitable to a white color by scanning the white roller. In the shuttle type, however, since the print head and the scanner module are established in parallel in the direction to which they perform the reciprocating movement, it is possible for the supporting plate to be contaminated by ink sprayed from the print head. Accordingly, the color of the supporting plate is processed as black. When scanning the document having a width smaller than the effective scan range of the scanner module, parts other than the document are data-processed suitably as black data.
Accordingly, since the black color means data in a black and white scanner, the data amount to be processed increases. As a result, the scanning time increases. Similarly in a color scanner, since the black part is treated as a part having a certain information, the scanning time also increases.
In addition, useless data which are processed in the parts other than the document consume much time when transmitting and receiving fax data, and exhaust much ink or toner of in the device which receives the data.